use of d:talib messes up attr, so this needs to be accessed as a direct variable

core/src/main/resources/lib/form/hetero-list.jelly

@@ -64,6 +64,11 @@ THE SOFTWARE.
       If true, insert new addition by default to their 'desired' location, which
       is the order induced by the descriptors.
     </st:attribute>
+    <st:attribute name="capture">
+      Config fragments from descriptors are rendered lazily by default, which means
+      variables seen in the caller aren't visible to them. This attribute allows you
+      to nominate additional variables and their values to be captured for descriptors.
+    </st:attribute>
   </st:documentation>
   <d:taglib uri="local">
     <d:tag name="body">
@@ -123,8 +128,9 @@ THE SOFTWARE.
       <j:set var="instance" value="${null}" />
       <j:forEach var="descriptor" items="${attrs.descriptors}" varStatus="loop">
         <div name="${attrs.name}" title="${descriptor.displayName}" tooltip="${descriptor.tooltip}" descriptorId="${descriptor.id}">
+          <j:set var="capture" value="${attrs.capture?:''}" />
           <local:body deleteCaption="${attrs.deleteCaption}">
-            <l:renderOnDemand tag="tr" clazz="config-page" capture="descriptor,it,instance">
+            <l:renderOnDemand tag="tr" clazz="config-page" capture="descriptor,it,instance,${capture}">
               <l:ajax>
                 <st:include from="${descriptor}" page="${descriptor.configPage}" optional="true" />
               </l:ajax>